As is well known, a plasma display device realizes an image on a plasma display panel (PDP) by employing plasma generated from gas discharge. Hence, the PDP generates a quantity of heat because of the high-temperature discharge gas.
As a discharge rate of a plasma display device increases to improve brightness, the heat generated at the PDP also increases accordingly. It is therefore a critical factor in the plasma display device to effectively dissipate the heat to the outside for good operation.
For that reason, in a conventional plasma display device, a PDP is usually attached to a chassis base formed out of materials of high thermal conductivity, with a heat-spreading sheet (or a heat-conduction sheet) provided between the PDP and the chassis base so the heat generated at the PDP can be dissipated to the outside via the heat-spreading sheet and the chassis base. The chassis base is typically formed by die-casting or press-working a metallic material such as aluminum. The heat-spreading sheet is typically formed of acryl- or silicone-based resin.
In addition, to improve the efficiency of the heat dissipation of the plasma display device as described above, it is important to effectively mount the heat-spreading sheet. That is, the heat-spreading sheet should be closely attached to both the PDP and the chassis base to improve the efficiency of the heat dissipation.
FIG. 6 is a fragmentary enlarged sectional view showing a plasma display device including a prior means of heat dissipation.
Since chassis base 102 as shown in FIG. 6 is produced by die-casting, the surface thereof that contacts heat-spreading sheet 104 may not be formed sufficiently flat, and it may have a partially curved or raised portion. When heat-spreading sheet 104 is attached to the uneven surface of chassis base 102 as the above, spaces are formed between the contact surfaces of heat spreading sheet 104 and chassis base 102, and air is filled therein to form air gap 108.
If the plasma display device is manufactured with air gap 108 between chassis base 102 and heat-spreading sheet 104, an overall efficiency of heat dissipation decreases, because heat conduction is not performed well enough through air gap 108. Such problems may also occur at the contacting parts of PDP 106 and heat-spreading sheet 104.
To resolve the above problems, when heat-spreading sheet 104 is attached to PDP 106 or chassis base 102, the pressure applied to heat-spreading sheet 104 can be increased to improve the adhesion rate thereof. However, the compression of PDP 106 due to the increased pressure may damage the inner spacers thereof and cause device failure.
Japanese patent publication laid-open No. 10-254372 discloses a plasma display device in which a thermal conduction sheet is provided with recessed sections and projecting sections on the surface contacting a PDP, to prevent the air gap from being formed between the PDP and the thermal conduction sheet. When the thermal conduction sheet is pressed against the PDP, the projecting sections are squeezed and expanded in lateral directions. During the expansion process, the recessed sections become air paths to push out air and are flattened.
The plasma display device described as above might be effective if the surface of the PDP (or the chassis base) contacting the heat-spreading sheet is extremely flat, but it is difficult to practically form the surface to an optimal flatness.
Accordingly, while the pressure applied to the heat-spreading sheet must be increased to improve the adhesion rate in this case, the problems of device failure caused by damaging the spacers still exist.